Cutting Apparatus For A Weaving Machine And Method For The Operation Of The Same

ABSTRACT

A cutting device ( 10 ) for a weaving machine ( 1 ) is presented which includes a first blade ( 12.1 ) on a first blade carrier ( 11.1 ), a second blade ( 12.2 ) on a movable and guided blade carrier ( 11.2 ) and a drive which cooperates with the movable blade carrier and includes a pneumatic actuator ( 14, 14′ ) and a spring ( 15 ) in order to part a weft thread ( 2 ) to be inserted into a shed or inserted into a shed. The spring ( 15 ) can be stressed by means of the pneumatic actuator ( 14, 14′ ) and the two blades ( 12.1, 12.2 ) can be closed by means of the action of the spring.

The invention relates to a cutting device for a weaving machine in accordance with the preamble of claim 1 and to a method for the operation of the same in accordance with the preamble of claim 8 and also to a weaving machine having such a cutting device and for carrying out such a method.

The various weaving machine types such as air jet weaving machines, rapier weaving machines or projectile weaving machines are named on the basis of the type of weft insertion. In rapier weaving machines the weft thread is for example inserted into a shed by means of a bringer rapier secured to a rod or a flexible tape and is taken over by a taker rapier at a transfer position in the middle part of the shed and conveyed further. The bringer rapier has the task of reliably gripping the weft thread presented by means of a thread presenter, of inserting the same into the shed and supplying it accurately to the taker rapier. The presented weft thread must in this arrangement be parted from the previously inserted weft thread before it can be inserted into the shed.

A cutting device is known from the document EP 683 256 A1 which includes a fixed blade and a movable blade. The movable blade is formed on a cranked lever which stands in connection with a pneumatic cylinder which contains a piston and a spring. The cutting device is held open in the rest state by the spring acting on the piston. For the cutting the pneumatic cylinder is loaded with compressed air via a control valve.

In modern rapier weaving machines the bringer rapier is moved during weft insertion at high speed. At the cutting time point the bringer rapier has a speed of typically 20 m/s i.e. it travels a distance of 2 cm in 1 ms. Accordingly, the cutting device must be able to cut the weft thread within a time span of a few ms because otherwise this is not cleanly cut but rather torn.

Customary cutting devices such as for example the cutting device known from EP 683 256 A1 have the disadvantage that they are too slow for modern weaving machines and in particular for modern rapier weaving machines.

It is the object of the invention to make available a cutting device for a weaving machine, in particular for a rapier weaving machine and a method for the parting of a weft thread inserted into a shed of a weaving machine, in particular of a rapier weaving machine, which are in a position to part the weft thread cleanly within a time interval of a few ms. A further object of the invention is to make available a weaving machine having such a cutting device and for carrying out such a method.

This object is satisfied in accordance with the invention by the cutting device defined in claim 1 and by the method defined in claim 8 for the parting of a weft thread inserted into a shed and also by the weaving machine defined in claim 12.

The cutting device in accordance with the invention for a weaving machine, in particular for a rapier weaving machine, includes a first blade on a first typically stationary blade carrier, a second blade on a second moveably guided blade carrier and a drive which cooperates with the second blade carrier and contains a pneumatic actuator and a spring in order to part a weft thread which is to be inserted into a shed or is inserted into a shed, wherein the spring can be stressed by means of the pneumatic actuator and the two blades can be optionally moved apart from one another and wherein the two blades can be closed by means of the action of force of the spring.

In an advantageous variant the second movable blade carrier is designed as a lever arm, in particular as a pivotable or pivotally mounted lever arm. In a further advantageous variant the pneumatic actuator is formed as a piston-in-cylinder unit or as a pneumatic rotary drive and/or the spring is designed as a compression spring, in particular as a spiral compression spring and the spring can for example be arranged in the piston-in-cylinder unit.

In a further advantageous variant the cutting device includes a control valve for the control of the pneumatic actuator, for example for the loading of the actuator with pressure in order to stress the spring and to optionally move the blades apart and/or for venting the actuator in order to trigger the cutting procedure.

In an advantageous embodiment the cutting device additionally includes a measurement pickup for the detection of the cutting time point and, if required, a regulating and control unit which can be connected with the measurement pickup and the control valve in order to automatically correct possible deviations from a preset cutting time point.

In a method in accordance with the invention for the parting of a weft thread to be inserted into or inserted into a shed of a weaving machine, in particular of a rapier weaving machine, a cutting device is provided which includes a first blade on a first typically stationary blade carrier, a second blade on a second movably guided blade carrier and a drive which cooperates with the second blade carrier and which includes a pneumatic actuator and a spring and the weft thread is parted by means of the cutting device. In addition the spring is stressed by means of the pneumatic actuator, the two blades are opened and the two blades are closed by means of force action of the spring for the parting of the weft thread.

In an advantageous variant of the method the pneumatic actuator is controlled by means of a control valve. In a further advantageous variant of the method the spring is stressed and the blades are optionally moved apart from one another in that the pneumatic actuator is loaded with pressure and/or the cutting procedure is triggered in that the pneumatic actuator is vented.

In an advantageous embodiment of the method the cutting time point is detected by a measurement pickup and possible deviations between the detected cutting time point and a preset cutting time point are automatically corrected.

The invention further includes a weaving machine, in particular a rapier weaving machine having a cutting apparatus in accordance with one of the above-described embodiments and variants and/or equipped for carrying out a method in accordance with the above description.

The cutting apparatus in accordance with the invention and the method in accordance with the invention for the parting of a weft thread inserted into a shed, or to be inserted into a shed, have the advantage that the spring can store sufficient potential energy in order to reliably part the weft thread, that the potential energy of the spring can at least be basically converted into energy of motion in less than 1 ms and that the pneumatic actuator and the pressure supply of the same can be designed such that it can stress the spring comparatively slowly, for example within 30 ms. In this respect considerable savings arise in comparison with a direct driving of the closing movement by the pneumatic actuator such as is described in the cited prior art.

The above description of the embodiments and variants merely serves as an example. Further advantageous embodiments proceed from the dependent claims and the drawing. Moreover, in the context of the present invention, individual features from the described and illustrated embodiments and variants can also be combined with one another in order to form new embodiments.

In the following the invention will be explained in more detail with reference to the embodiment and to the drawing in which are shown:

FIG. 1 a schematic view of an embodiment of a weaving machine such as is used in connection with the present invention,

FIG. 2 a detailed view of a bringer rapier and of a cutting device from the embodiment of FIG. 1 prior to the parting of the weft thread,

FIG. 3 a schematic view of an embodiment of a cutting device in accordance with the present invention,

FIG. 4 a schematic view of a second embodiment of a cutting device in accordance with the present invention and

FIG. 5 a perspective view of a third embodiment of a cutting device in accordance with the present invention.

FIG. 1 shows a schematic view of an embodiment of a weaving machine such as is used in connection with the present invention. The weaving machine 1 is designed in the illustrated embodiment as a rapier weaving machine and includes a bringer rapier 3 and a taker rapier 4 which respectively contain a thread clamp in order to receive and firmly hold a weft thread 2 to be inserted. The bringer rapier and the taker rapier are typically secured to a respective non-illustrated rod or to a non-illustrated flexible tape which are displaceable and driven in the direction of insertion. By means of the bringer rapier the weft thread can be inserted into a shed and can be taken over by the taker rapier at a transfer point in the middle part of the shed and conveyed further. Furthermore, the weaving machine can for example include a thread spool 2 a and a thread store 2 b from which the weft thread 2 can be drawn off and also, if required, a thread brake 5 and/or a sensor 6 for the measurement of the thread tension force and/or optionally a thread presenter or a colour selector 7 having a plurality of thread presenters and/or a control unit 9 for the control of the weft insertion.

In addition the weaving machine includes a cutting device 10 in order to part the weft thread 2, for example as shown in FIG. 1, from the previously inserted weft thread before it is inserted into the shed. FIG. 2 shows a detailed view of a bringer rapier 3 and a cutting device 10 from the embodiment of FIG. 1 before the parting of the weft thread. The weft thread which is to be inserted and which has been taken up by the bringer rapier 3 is moved forwardly by the bringer rapier 3 in the weft insertion direction. FIG. 2 shows the bringer rapier at three different points in time as shown by full and broken outlines. During weft insertion the weft thread 2 is held in a thread clamp of the bringer rapier and is deflected at a deflection point 3 a in the bringer rapier. On one side of the bringer rapier the weft thread is drawn off from the thread store not shown in FIG. 2 via a thread presenter 7 a whereas, on the other side it is still connected with the previously inserted weft thread as shown in FIG. 2. At this side a cutting device 10 is therefore provided in order to part the weft thread to be inserted. In this connection the cutting time point and the time interval required for the parting is critical since, if the weft thread is parted too early, too little tension can be exerted on it in order to pull it reliably into the thread clamp during the take-up and, on the other hand, if it is parted too late the weft thread is torn in the cutting device.

FIG. 3 shows a schematic view of an embodiment of a cutting device 10 in accordance with the present invention. In the illustrated embodiment the cutting device includes a first blade 12.1 on a first typically stationary blade carrier 11.1, a second blade 12.2 on a movable and guided blade carrier 11.2 and a drive which cooperates with the movable blade carrier and contains a pneumatic actuator 14 and a spring 15 in order to part a weft thread which is to be inserted into a shed or is inserted into a shed, with the spring 15 being able to be stressed by means of a pneumatic actuator 14 and with the two blades 12.1, 12.2 optionally being movable apart and wherein the two blades can be closed by means of the force action of the spring.

In an advantageous variant the movable blade carrier is designed as a lever arm, for example as a pivotable or pivotally mounted lever arm. Naturally it is also possible to use a linearly guided movable blade carrier in place of a lever arm.

In a further advantageous variant the pneumatic actuator can, as shown in FIG. 3, be designed as a piston-in-cylinder unit 14 having a pressure cylinder 14 a and a piston 14 b movable in the same in the longitudinal direction. If required the spring 15 can be designed as a compression spring, for example as a helical compression spring wherein it can for example be disposed in the piston-in-cylinder unit as shown in FIG. 3.

In a further advantageous variant the cutting device 10 includes a control valve 16 for the control of the pneumatic actuator 14, for example for the application of pressure to the actuator in order to stress the spring 15 and optionally move the blades apart and/or if required, for venting the actuator 14 in order to trigger the cutting process. The control valve can for this purpose for example be designed as a 3/2 way valve. Moreover, if required, a pressure line or a pressure source 17 can be provided in order to supply the pneumatic actuator 14 and or the control valve 17 with compressed air.

FIG. 4 shows a schematic view of a second embodiment of a cutting device 10 in accordance with the present invention. In the embodiment shown the cutting device includes a first blade 12.1 on a first typically stationary blade carrier 11.1, a second blade 12.2 on a movable and guided blade carrier 11.2 and a drive which cooperates with the movable blade carrier and includes a pneumatic actuator 14 and a spring 15 in order to part a weft thread which is to be inserted into the shed or is inserted into a shed, with the spring 15 being able to be stressed by means of the pneumatic actuator 14 and with the two blades 12.1 and 12.2 being optionally movable apart and wherein the two blades can be closed by means of the force action of the spring.

In an advantageous variant the movable blade carrier is designed as a lever arm, for example as a pivotable or pivotally mounted lever arm. In a further advantageous variant the pneumatic actuator can be designed as a pneumatic rotary drive 14′ as shown in FIG. 4. The spring 15 can for example be designed as a compression spring, for example as a spiral compression spring. It is however also possible for example to design the spring 15 as a torsion spring and if required to integrate it into the pneumatic rotary drive.

In a further advantageous variant the cutting device 10 includes a control valve 16 for the control of the pneumatic actuator 14. For details regarding the control valve reference is made to the above description of the embodiment shown in FIG. 3.

FIG. 5 shows a perspective view of a third embodiment of a cutting device 10 in accordance with the present invention. In the embodiment shown the cutting device includes a first blade 12.1 on a first typically stationary blade carrier 11.1, a second blade 12.2 on a movable and guided blade carrier 11.2 and a drive which cooperates with the movable blade carrier, which includes a pneumatic actuator 14 and a spring 15 in order to part a weft thread 2 which is to be inserted into shed or is inserted into a shed, with the spring 15 being able to be stressed by means of the pneumatic actuator 14 and with the two blades 12.1, 12.2 optionally being movable apart and wherein the two blades can be closed by means of the force action of the spring.

In an advantageous variant the movable blade carrier is designed as a lever arm, for example as a pivotable or pivotally mounted lever arm. Naturally it is also possible, for example, to provide a linearly guided movable blade carrier in place of a lever arm.

In a further advantageous variant the pneumatic actuator can be designed as a piston-in-cylinder unit 14 as shown in FIG. 5. If required the spring 15 can be designed as a compression spring, for example as a helical compression spring, and this can for example be coaxially arranged with the piston-in-cylinder unit, as shown in FIG. 5. The movement of the piston in the piston-in-cylinder unit 14 can, for example, be transmitted by means of a piston rod 14 c to a cranked lever 14 d as shown in FIG. 5 with the cranked lever 14 d in turn being connected to the movable blade carrier 11.2. Moreover a thread presenter 7 a is shown in FIG. 5 which is not however a part of the cutting device 10.

In a further advantageous variant the cutting device 10 includes a control valve 16 for the control of the pneumatic actuator 14. For details regarding the control valve reference is made to the above description of the embodiment shown in FIG. 3.

Independently of the embodiment and the specific embodiments and variants the cutting device 10 can additionally include a measurement pickup 13 for detecting the cutting time point and, if required, a regulation and control unit 18 which, if required, can be connected to the pickup and the control valve 16 in order to correct possible deviations from a preset cutting time point. Possible deviations between the detected and the preset cutting time point are principally caused by the cutting device in that, for example, the switching time of a control valve or the venting of the pneumatic actuator can change or in that the frictional conditions in the pneumatic actuator or between the blades can change, for example in the period after a machine stop or as a consequence of temperature changes or wear. The described regulation of the cutting time point has the advantage that it can be precisely observed, even when the time interval between the triggering of the cutting procedure and the cutting time point i.e. the point in time at which the weft thread is parted, is subject to changes in practical operation.

An embodiment of the method of the invention for the parting of a weft thread 2 which is to be inserted into a shed of a weaving machine or is inserted into a shed of a weaving machine, in particular of a rapier weaving machine, is described in the following with reference to FIGS. 3 to 5. In the method a cutting device 10 is provided which includes a first blade 12.1 on a first typically stationary blade carrier 11.1, a second blade 12.2 on a movable and guided blade carrier 11.2 and a drive which cooperates with the movable blade carrier and contains a pneumatic actuator 14, 14′ and a spring 15, and the weft thread 2 is parted by means of the cutting device 10. In addition the spring 15 is stressed by means of a pneumatic actuator 14, 14′, the two blades 12.1, 12.2 are opened and the two blades are closed by means of the force action of the spring for the parting of the weft thread.

In an advantageous variant of the method the pneumatic actuator 14, 14′ is controlled by means of the control valve 16. In a further advantageous variant of the method the spring 15 is stressed and the blades are optionally moved apart in that the pneumatic actuator is loaded with pressure and/or the cutting procedure is triggered in that the pneumatic actuator is vented.

In an advantageous embodiment of the method the cutting time point is detected with a measurement pickup 13 and possible deviations between the detected cutting time point and a preset cutting time point are corrected.

The cutting device in accordance with the invention and the method in accordance with the invention for the parting of a weft thread in a weaving machine permit the weft thread to be parted within a few ms, thanks to the spring drive of the closing movement, so that it can be cleanly cut, even when the cutting device is used on a rapidly running rapier weaving machine. Moreover, the described regulation for the cutting time point enables the same to be more precisely maintained even when the time interval between triggering of the cutting procedure and the time at which the weft thread is parted changes in practical operation. 

1. Cutting device (10) for a weaving machine (1), in particular a rapier weaving machine including a first blade (12.1) on a first blade carrier (11.1), a second blade (12.2) on a movable and guided blade carrier (11.2) and a drive which cooperates with the movable blade carrier and includes a pneumatic actuator (14, 14′) and a spring (15) in order to part a weft thread (2) to be inserted into a shed or inserted into a shed, characterized in that the spring (15) can be stressed by means of the pneumatic actuator (14, 14′) and in that the two blades (12.1, 12.2) can be closed by means of the force action of the spring.
 2. Cutting device in accordance with claim 1, wherein the movable blade carrier (11.2) is designed as a lever arm, in particular as a pivotably or pivotally mounted lever arm.
 3. Cutting device in accordance with claim 1, wherein the pneumatic actuator is designed as a piston-in-cylinder unit (14, 14 a, 14 b) or as a pneumatic rotary drive (14′).
 4. Cutting device in accordance with claim 1, wherein the spring (15) is formed as a pressure spring, in particular as a helical pressure spring and wherein the spring is in particular disposed in the piston-in-cylinder unit (14, 14 a, 14 b).
 5. Cutting device in accordance with claim 1 including a control valve (16) for the control of the pneumatic actuator (14, 14′), in particular for applying pressure to the actuator in order to stress the spring (15) and optionally to move the blades apart and/or for venting the actuator in order to trigger the cutting procedure.
 6. Cutting device in accordance with claim 1, additionally including a measurement pickup (13) for detecting the cutting time point.
 7. Cutting device in accordance with claim 6, additionally including a regulation or controlling unit (18) which is connected to the measurement pickup (13) and to the control valve (16) to automatically correct possible deviations from a preset cutting time point.
 8. Method for the parting of a weft thread (2) to be inserted into or inserted into a shed with a weaving machine (1), in particular of a rapier weaving machine, in which a cutting device (10) is provided which includes a first blade (12.1) on a first blade carrier (11.1), a second blade (12.2) on a movable and guided blade carrier (11.2) and a drive which cooperates with the movable blade carrier and which includes a pneumatic actuator (14, 14′) and a spring (15) and in which the weft thread (2) is parted by means of the cutting device (10), characterized in that the spring (15) is stressed by means of the pneumatic actuator (14, 14′) and the two blades (12.1, 12.2) are opened and in that the two blades are closed by means of the action of force of the spring for the parting of the weft thread (2).
 9. Method in accordance with claim 8, wherein the pneumatic actuator (14, 14′) is controlled by means of a control valve (15).
 10. Method in accordance with claim 8, wherein the spring (15) is stressed and the blades (12.1, 12.2) are optionally moved apart in that the pneumatic actuator is acted on by pressure and/or the cutting procedure is triggered in that the pneumatic actuator (14, 14′) is vented.
 11. Method in accordance with claim 8, wherein the cutting time point is detected with a measurement pick-up (13) and possible deviations between the detected cutting time point and a preset cutting time point are automatically corrected.
 12. A rapier weaving machine comprising a cutting device (10) constructed in accordance with claim
 1. 